KABUL -- Hundreds of Afghan protesters poured into the streets of the northeastern provincial capital Assad-Abad on March 2 over the death of nine civilians killed in a NATO air strike, RFE/RL's Radio Free Afghanistan reports.

NATO officially apologized on March 2 for what it called an "accident." It said in a statement that "[the NATO-led] International Security Assistance Force apologizes and accepts responsibly for the civilian causalities" in Kunar Province on March 1.

The alliance expressed "deep grief" for the "tragedy" and apologized to the Afghan government, the people of Afghanistan, and the families of the victims.

Afghan President Hamid Karzai released a statement condemning the deaths.

It is the second time in two weeks that Kunar residents have criticized NATO-led troops for causing civilian causalities in their counterinsurgency operation near the country's border with Pakistan.

Angry demonstrators on March 2 carried photos of children who died in the air strike. They also chanted slogans against the U.S. and Afghan governments.

A protester told RFE/RL that at least nine children were killed and another was severely injured. He said all the victims of the last two incidents were "absolutely" civilians.

"Our kids were killed in the nearby forest when they went out to collect firewood. It was a vicious attack," he said.

Another demonstrator told RFE/RL that the demonstrations will continue until the perpetrators of such acts and "the murderers" of the children are brought to justice.

A member of the provincial council in Kunar condemned the killing of innocent Afghans by foreign troops, but also called on Taliban militants to stop using civilians as human shields.